A method of recording, storing, analyzing, and displaying changes in a womans basal body temperature includes the steps of: (a) recording with an intelligent, preprogrammed thermometer the womans orally-measured temperature (b) storing in the thermometer the womans temperature to create a stored temperature reading (c) repeating steps (a) and (b) (d) analyzing inside the thermometer the significance of any changes in the stored temperature readings and (e) displaying the changes in the womans basal body temperature, and displaying an analysis of those changes, on the thermometer, and on any electronic device connected to the thermometer. In other features of the invention, steps (a) and (b) are repeated daily when the woman first awakes from her nights sleep, and the woman first inputs into the thermometer data about herself, including at least her year of birth, her height, her weight, her body mass index, and her current and past menstruation data.
